The present invention relates generally to combustion-powered fastener-driving tools, and more particularly to a new and improved lock-out mechanism which is operatively connected to the trigger mechanism of the combustion-powered fastener-driving tool, and which is also adapted for operative engagement with the annular sleeve member of the combustion-powered fastener-driving tool, wherein the annular sleeve member of the combustion-powered fastener-driving tool is integrally connected to the axially movable work-piece-contacting element of the combustion-powered fastener-driving tool so as to be axially movable with the axially movable workpiece-contacting element in order to effectively be disposed at combustion chamber OPEN and CLOSED positions, and wherein further, the new and improved lock-out mechanism is operatively engaged with the annular sleeve member of the combustion-powered fastener-driving tool so as to effectively prevent movement of the annular sleeve member of the combustion-powered fastener-driving tool from the combustion chamber CLOSED position to the combustion chamber OPEN position when the trigger mechanism of the combustion-powered fastener-driving tool is disposed in its actuated state, and yet, the new and improved lock-out mechanism is able to be readily disengaged from the annular sleeve member of the combustion-powered fastener-driving tool when the trigger mechanism of the combustion-powered fastener-driving tool is released from its actuated state.
Combustion-powered fastener-driving tools are of course well known, and examples of such combustion-powered fastener-driving tools are disclosed within U.S. Pat. No. 6,145,724 which issued to Shkolnikov et al. on Nov. 14, 2000, U.S. Pat. No. 5,909,836 which issued to Shkolnikov et al. on Jun. 8, 1999, U.S. Pat. No. 5,197,646 which issued to Nikolich on Mar. 30, 1993, and U.S. Pat. No. 4,483,474 which issued to Nikolich on Nov. 20, 1984. In addition to the multitude of interactive operative components of such combustion-powered fastener driving tools which are obviously provided upon the tools in order to permit such combustion-powered fastener driving tools to operate in accordance with particular modes of operation desired or required by workmen or operators located at various job sites, the combustion-powered fastener-driving tools also usually incorporate a safety feature which effectively comprises a lock-out mechanism by means of which the trigger mechanism of the combustion-powered fastener-driving tool cannot be actuated if the workpiece-contacting element of the combustion-powered fastener-driving tool has not been previously disposed in contact with the substrate or workpiece into which the fasteners are to be driven, and in a similar manner, the annular sleeve member of the combustion-powered fastener-driving tool, which has been previously axially moved to a position at which the combustion chamber is effectively CLOSED so as to permit a combustion cycle to occur, cannot be moved to a position at which the combustion chamber is effectively OPENED as long as the tool trigger mechanism is still disposed in its actuated state. A lock-out mechanism of the foregoing type is disclosed, for example, within the aforenoted patent to Nikolich, U.S. Pat. No. 5,197,646.
More particularly, as disclosed within FIG. 1, which corresponds to FIG. 1 of the aforenoted patent to Nikolich, it is noted that the combustion-powered fastener-driving tool 10 briefly comprises a housing structure 12 which includes a principal portion 14 and a handle portion 16. The housing structure 12 also has incorporated therein a nail-feeding mechanism 20 which is adapted to successively feed a plurality of nails N into a nosepiece section 50 of the tool 10 at which a piston-driver blade assembly 40-42 can act thereon so as to successively drive the nails N into the underlying substrate or workpiece W. The piston 40 is movably disposed within a piston chamber 32 which is defined within a cylinder body 30, and a valve member-sleeve assembly 60-62 annularly surrounds the cylinder body 30. A combustion chamber 70 is effectively defined within an upper region of the combustion-powered fastener-driving tool 10 by means of the upper portion of the valve member-sleeve assembly 60-62, and a fan 72, powered by means of a motor 74, is disposed within the combustion chamber 70. The valve member-sleeve assembly 60-62 is axially movable with respect to the cylinder body 30 so as to be alternatively disposed at an upper combustion chamber CLOSED position and a lower combustion chamber OPENED position, and a workpiece contacting element 82 is movably mounted upon the nosepiece section 50. The workpiece contacting element 82 is operatively connected to the valve member-sleeve assembly 60-62 through means of a linkage 80 and a valve member-sleeve assembly actuating element 84, and accordingly, when the workpiece contacting element 82 is pressed into engagement with the workpiece W, the valve member-sleeve assembly 60-62 is moved from its aforenoted lower combustion chamber OPENED position to its upper combustion chamber CLOSED position.
In order to fire the combustion-powered fastener-driving tool 10, the same is provided with a trigger mechanism 120 which is normally biased to a lower or outward deactuated position, as viewed in FIG. 1, by means of a coil spring 122. A lock-out mechanism in the form of a pawl 130 has a first radially outer end portion 136 thereof pivotally mounted within the trigger mechanism 120, while a second radially inner end portion 131 thereof is adapted to be disposed within an aperture 140 of the valve member-sleeve assembly 60-62 when the valve member-sleeve assembly 60-62 has been moved to its upper combustion chamber CLOSED position, as a result of the engagement of the workpiece contacting element 82 with the workpiece W, and when the trigger mechanism 120 has also been moved to its upper or inward actuated position. Leg portions 134 of the pawl 130 are adapted to be disposed within grooved portions 132 formed within opposite halves of the housing 12 which form the handle portion 16 so as to permit the pawl 130 to freely undergo slidable and pivotal movements. A wear plate 142 is fixedly mounted upon an external side wall portion of the valve member-sleeve assembly 60-62, and accordingly, as long as the trigger mechanism 120 is maintained in its upper or inward actuated position, the valve member-sleeve assembly 60-62 will effectively be maintained in a LOCKED combustion-enabling position. When, however, the valve member-sleeve assembly 60-62 is disposed at its lowered combustion chamber OPENED position, as when the workpiece contacting element 82 has not been or is no longer properly engaged with the workpiece W, the inner end portion 131 of the pawl 130 will engage the wear plate 142 whereby the trigger mechanism 120 cannot in fact be moved from its lower or outward deactuated state to its upper or inward actuated state, thereby effectively preventing the undesirable firing of the combustion-powered fastener-driving tool 10.
While the aforenoted lock-out mechanism has performed quite satisfactorily, recent developments in connection with the design and interrelated arrangement of the various structural components of combustion-powered fastener-driving tools has resulted in the fabrication of high-energy tools which create or generate an enhanced level of force or power for driving the fasteners into the underlying substrate or workpiece. Under such operative conditions, the provision of a lock-out mechanism, of the type disclosed within the aforenoted patent to Nikolich, sometimes becomes somewhat difficult to manipulate or maintain at its combustion-chamber CLOSED position, during the firing or discharge of a fastener from the fastener-driving tool, in view of the fact that a substantially large portion of the operating force, required to manipulate or maintain the lock-out mechanism at such combustion-chamber CLOSED position, must simply be borne by means of the operator""s finger which is operatively engaged with the trigger mechanism. Accordingly, in view of this ergonomically undesirable arrangement, the operator often suffers fatigue and discomfort. A solution to this problem has been sought by operatively reorienting the disposition of the lock-out mechanism, and by altering the support of the same during its movements attendant the actuation and deactuation of the tool trigger mechanism in order to effectively remove a substantial portion of the manipulation or maintenance forces, to be imparted to the lock-out mechanism pawl, from the trigger mechanism. Unfortunately, such design changes have sometimes resulted in the lock-out mechanism becoming jammed or frozen whereby, for example, the lock-out mechanism would not reliably move to its retracted or withdrawn position so as to, in turn, permit the valve member-sleeve assembly to move to its combustion chamber OPENED position in order to permit combustion product exhaust and air intake fluid flows to properly occur.
A need therefore exists in the art for a new and improved lock-out mechanism which is operatively connected to the trigger mechanism of the combustion-powered fastener-driving tool, and which is uniquely supported upon the handle portion of the tool housing, so as to be operatively engaged with the annular sleeve member of the combustion-powered fastener-driving tool without requiring an inordinate amount of force to be maintained upon the trigger mechanism of the tool in order to maintain the lock-out mechanism engaged with the annular sleeve member of the tool, whereby the annular sleeve member of the combustion-powered fastener-driving tool can be maintained at its combustion chamber CLOSED position and effectively prevented from undergoing movement from the combustion chamber CLOSED position to the combustion chamber OPEN position when the trigger mechanism of the combustion-powered fastener-driving tool is disposed in its actuated state, and yet, the new and improved lock-out mechanism is able to be readily disengaged from the annular sleeve member of the combustion-powered fastener-driving tool, when the trigger mechanism of the combustion-powered fastener-driving tool is released from its actuated state, so as not to undesirably prevent movement of the annular sleeve member from the combustion chamber CLOSED position to the combustion chamber OPENED position.
Accordingly, it is an object of the present invention to provide a new and improved lock-out mechanism for use in conjunction with a combustion-powered fastener-driving tool.
Another object of the present invention is to provide a new and improved lock-out mechanism for use in conjunction with a combustion-powered fastener-driving tool wherein the new and improved lock-out mechanism effectively overcomes the various operational drawbacks and disadvantages characteristic of conventional PRIOR ART lock-out mechanisms.
An additional object of the present invention is to provide a new and improved lock-out mechanism which is particularly useful in conjunction with high-energy combustion-powered fastener-driving tools which create or generate an enhanced level of force or power for driving the fasteners into an underlying substrate or workpiece.
A further object of the present invention is to provide a new and improved lock-out mechanism which is particularly useful in conjunction with high-energy combustion-powered fastener-driving tools, which create or generate an enhanced level of force or power for driving the fasteners into an underlying substrate or workpiece, wherein the new and improved lock-out mechanism is mounted and supported within the handle portion of the combustion-powered fastener-driving tool in such a manner as to bear a substantially large portion of the load forces required to maintain the lock-out mechanism at the combustion-chamber CLOSED position so as to in turn reduce or relieve the necessity of having the operator-manipulated trigger mechanism from bearing such load forces required to maintain the lock-out mechanism at the combustion-chamber CLOSED position.
A last object of the present invention is to provide a new and improved lock-out mechanism which is particularly useful in conjunction with high-energy combustion-powered fastener-driving tools, which create or generate an enhanced level of force or power for driving the fasteners into an underlying substrate or workpiece, wherein the new and improved lock-out mechanism is mounted and supported within the handle portion of the combustion-powered fastener-driving tool in such a manner as to bear a substantially large portion of the load forces required to maintain the annular sleeve member of the combustion-powered fastener-driving tool at the combustion-chamber CLOSED position so as to in turn reduce or relieve the necessity of having the operator-manipulated trigger mechanism from bearing such load forces required to maintain the annular sleeve member of the combustion-powered fastener-driving tool at the combustion-chamber CLOSED position, and wherein further, the new and improved lock-out mechanism is also able to be readily disengaged from the annular sleeve member of the combustion-powered fastener-driving tool, when the trigger mechanism of the combustion-powered fastener-driving tool is released from its actuated state, so as not to undesirably prevent movement of the annular sleeve member from the combustion chamber CLOSED position to the combustion chamber OPENED position.
The foregoing and other objectives are achieved in accordance with the teachings and principles of the present invention through the provision of a new and improved lock-out mechanism, for use in conjunction with a combustion-powered fastener-driving tool, which comprises a lock-out bar wherein a first end portion of the lock-out bar is pivotally connected to the trigger mechanism of the combustion-powered fastener-driving tool, while the second opposite end portion of the lock-out bar comprises a substantially C-shaped loop section which is oriented at an angle of substantially 90xc2x0 with respect to the axial extent of the annular sleeve member of the combustion-powered fastener-driving tool. In conjunction with the aforenoted 90xc2x0 orientation of the C-shaped loop section with respect to the axial extent of the annular sleeve member of the combustion-powered fastener-driving tool, a distal end portion of the C-shaped loop section is slidably supported between a pair of guide rails which are formed upon internal surface regions of each housing half forming the handle portion of the combustion-powered fastener-driving tool. In this manner, the lock-out bar and the guide rails of the handle housing halves bear substantially the entire portion of the load forces necessary to maintain the annular sleeve member of the combustion-powered fastener-driving tool at the combustion chamber CLOSED position so as to, in turn, effectively obviate the need for the operator-manipulated trigger mechanism from bearing such load forces.
In addition, in order to readily facilitate the disengagement of the lock-out bar from its engaged position with the annular sleeve member of the combustion-powered fastener-driving tool, so as to permit the annular sleeve member of the combustion-powered fastener-driving tool to be moved from the combustion chamber CLOSED position to the combustion chamber OPENED position, the substantially C-shaped loop section of the lock-out bar is provided with a member which is rotatably mounted thereon and which is also rotatably engaged with a wear plate portion of the annular sleeve member. Accordingly, when the trigger mechanism of the combustion-powered fastener-driving tool is no longer maintained at its actuated position, the rotatable member of the lock-out bar readily facilitates the slidable disengagement of the lock-out bar with respect to the wear plate portion of the annular sleeve member so as to effectively permit the annular sleeve member to be released or moved from the combustion chamber CLOSED position to the combustion chamber OPENED position.